The Dow ended Monday with a drop of 4.6%, or 1,175 points. At one point during the trading day the Dow had fallen by nearly 1,600 points. The S&P 500 shed 4.1% and the Nasdaq fell 3.8%.

The shock decline was nowhere close to the scale of destruction seen on Black Monday in 1987 or the financial crisis of 2008. But for investors lulled to sleep by the steady upward climb since Election Day in 2016, it was alarming.

"This is a rather abrupt reminder of what volatility looks like. Nothing has changed in economic terms," said Paul Donovan, global chief economist at UBS Wealth Management.

2. Panic abroad:Europe and Asia followed the lead of U.S. markets on Tuesday, posting major losses. The Hang Seng in Hong Kong dropped 5.1% and Japan's Nikkei shed 4.7%.

Most European markets were falling by about 2% in early trade.

3. Lulu under pressure: Laurent Potdevin, the chief executive of Canadian yoga retailer Lululemon, is out after the company said he "fell short" of its standards of conduct.

"Lululemon expects all employees to exemplify the highest levels of integrity and respect for one another, and Mr. Potdevin fell short of these standards of conduct," the company said in a release Monday afternoon.

The company didn't say how Potdevin, who has been CEO since 2014, fell short of its standards.

Shares in Lululemon were set to decline at the open.

4. Media earnings: Several big media companies report earnings this week: Disney on Tuesday, 21st Century Fox on Wednesday and News Corp and Viacom on Thursday.